Inorganic photoconductive materials such as selenium, cadmium sulfide and zinc oxide have been conventionally used as electrophotographic light sensitive materials. Recently, many suggestions that organic photoconductive materials can be used as electrophotographic photoreceptors have been made. In particular, research and development on a function separated type photoreceptor in which functions of light carrier generation and transportation are divided into separate materials, i.e., charge generating materials and charge transporting materials, has recently gained popularity and has already been used practically. The use of charge transporting material such as, various hydrazones, stilbenes and triphenylamine derivatives have been proposed. In addition, benzidine derivatives useful as charge transporting materials have been described, e.g., in JP-A-61-132954 (The term "JP-A" as used herein means as "unexamined, published Japanese patent application").
Although, these organic photoconductive materials have advantages such as low manufacturing costs, good safety and high production rate, they are still inferior to inorganic photoconductive materials with respect to light response rate, stability, mechanical durability or the like. Thus, materials having better characteristics have been desired.